Conventionally, many kinds of industrial fabrics such as a fabric for making papers, a fabric for unwoven fabric, a fabric for hydrating sludge, a belt for manufacturing building material, a conveyor belt have been widely known. Each of these industrial fabrics has been formed in an endless form to be used with being mounted on machines such as a paper making machine, a hydrator.
Here, with respect to a method of processing these industrial fabrics in endless forms, so-called weave-patch method, a method in which loops formed using warps of the industrial fabrics are mated, at both ends, and then, a core wire for binding is penetrated into a common hole formed by the loops, a method in which spiral loops arranged at both ends of the fabric are mated with each other, and then, the core wire is introduced into these spiral loops, and a method in which metal hooks mounted on both ends of the fabric called clipper ratings are mated with each other, and then, the core wire is introduced into these metal hooks haven been widely known. These many methods have been adopted in accordance with applications.
Among these methods, it is technical possible to desirably form in either an endless form, or an end form by inserting into the core wire of binding, or removing the core wire, in the method in which the loops formed at the ends of the industrial fabric are mated with each other to form an endless form. If the fabric can desirably be formed in either an endless form, or an end form, when the fabric is mounted on a machine, the end of the fabric can be wound between rolls of the machine, and then, the fabric can be formed in an endless form with being wound around the machine.
For instance, the machine can be operated after an old-used industrial fabric is formed to possess ends with being mounted on the machine, and then, one end of a new industrial fabric to be mounted is bound to one of the ends. This causes the industrial fabric to shift between the rolls of the machine to be wound between the rolls, whereby the old-used industrial fabric can be removed and the new industrial fabric can be formed in an endless form to be mounted on the machine after the fabric is wound around in an entire form.
On the other hand, in case of the weave-patch method in which it is not feasible to desirably form either the endless type or the type in which ends are included, a so-called cantilever method in which the roll of the machine is supported at one side, while a poll etc. hinders the insertion of the industrial fabric, at the other side is removed, and then, the industrial fabric is introduced form the one side of the machine in the widthwise direction to be wound around has to be adopted. However, in order to effect weave-patch by the cantilever method, a specific structure for detaching the fabric is essential for the machine itself, a defect that the cost for manufacturing the machine is raised. In addition, another defect that the machine becomes bulky, or that a wide space for arranging the machine can be caused. Further, in a case where the heavy or long industrial fabric is used, it is technically difficult to introduce the fabric, and thus, it is not suitable.
Such being the case, such a cantilever method has not been adopted in fact except for the fabric for making web used at the web-making section of the paper making machine where the surface smoothness is extremely important. Therefore, a method in which spiral loops or metal hooks are formed at end portions has been adopted as a method of forming the fabric in an endless form.
However, in the above method, additional spiral wires or metal hooks which has a different structure or material form the yarns constituting the industrial fabric has to be mounted. In addition, in a case where the loop is formed, the loop forming portion and the ordinary portion are different from each other and the loop protrudes from the end portion, so that the structure of the binding portion is fundamentally different from the ordinary portion.
In view of the above technical problems, a binding loop structure for the industrial fabric has been proposed in the Patent Publications 1 and 2. In the binding loop structure for the industrial fabric, the warp constituting the fabric is folded back at the end portion to form a plurality of binding loops, and then, such a plurality of binding loops are aligned with each other to form a hole, followed by the fact that the core wire is introduced into such a hole. FIG. 6 is a plain photograph showing an example of the conventional binding structure of the industrial fabric. As shown in FIG. 6, the core wire is introduced into the common hole formed by the loops.
However, in the above binding loop structure of the industrial fabric, additional process in which a plurality of bonding loops are aligned with each other, and then holes which are formed by the loops and through which the core wire is penetrated have to be arranged before the fabric is processed in an endless form. In such a case, it becomes impossible to smoothly carry out the insertion of the core wire into the holes unless any one of the holes of the loops gets offset. In addition, if the core wire is introduced into the loops any one of which is loose, the boding loop can protrude toward the upper layer, or a gap can be caused. Such problems can bring about a serious problems such as a marking or a decrease of the rigidity.
That is why a highly-skilled technique and much time are essential for the process for making a plurality of binding loops aligned with each other and arranging the holes into which the core wire is introduced, so that the degree of the technical difficulty for the method of processing the endless form, whereby it takes a lot of time for the boding operation.
In addition, in the industrial multi-layered fabric, since the binding loop formed by the upper surface side warp and the binding loop formed by the lower surface side warp are overlapped with each other at the loop forming portion, the net thickness of the fabric is thicker than that of the ordinary portion. Such a problem has not been solved by the so far binding structure of the industrial fabric.
Further, in some of the present industrial fabrics, the upper surface side fabric is constituted by yarns made of fluorine resin in order to deal with the dirt problem, while the lower surface side fabric is constituted by yarns made of polyethylene terephthalate (PET) in order to fulfill the required physical properties such as rigidity.
If the method of forming loops is applied to the binding structure of the both end portions of such industrial fabrics, the technical problem that the loop forming portion and the ordinary portion have different structure from each other is raised. More specifically, loop portions are formed at the lower surface side warp in addition to the upper surface side warp in order to increase the strength of the loop forming portions, so that the lower surface side warp formed of PET, etc. becomes exposed to the surface, whereby the anti-dirt effect at the binding portion becomes deteriorated.
On the other hand, as disclosed by the binding portion in Patent Publication 2, the binding loop structure positively concealing the loop forming portion by the upper surface side weft is known. However, the invention of the binding loop described in Patent Publication 2 does not pay attention to the fact that the loop forming portion is kept not exposed to the surface of the lower surface side fabric.